Optical flow image analysis of facial expressions of human emotion: forensic applications.

The objective of this study was to induce emotions in individuals to determine if specific facial movements could be detected and analysed by the optical flow technique. This analysis is in the form of motion vector plots. The procedure ascertains if specific emotions can be defined as a set of facial movements which are common to most people when they experience a particular emotion. 'Emotion vector maps' would then be established for specific emotions. These vector sets could then be applied to automated facial image analysis for security/forensic purposes. Individuals were videotaped while watching emotion-inducing short films. After the viewing of each short film, volunteers completed a brief self-reporting questionnaire to establish the emotions they experienced. The image sequences were then analysed according to emotion, by using optical flow analysis. Results were statistically analysed. Trends and analyses are presented in relation to security and video surveillance. Issues and the development of pattern recognition systems applied to human facial images for security purposes are briefly discussed.